1. Field of the Invention
The present invention relates to in-vehicle radar apparatuses and methods for manufacturing the apparatuses, and more particularly, to an in-vehicle radar apparatus having a reference plane for adjusting a beam axis and a method for manufacturing the same.
2. Description of the Related Art
An in-vehicle radar apparatus has been developed in order to secure vehicle travel safety. The in-vehicle radar apparatus emits a beam of radio waves in the millimeter wavelength range or laser, and detects a target such as another vehicle from the beam reflected by the target. It is desired to control the beam emission angle (beam axis) with respect to the vehicle for improvements in precision. In practice, poor accuracy in attachment of an antenna to a casing may cause the angle of the beam axis with respect to the casing to deviate from the designed value. Thus, the beam axis cannot be controlled precisely when the in-vehicle radar apparatus is attached to the vehicle with the casing being used as a reference plan. Japanese Patent Application Publication No. 2004-347512 discloses a reference plane aligned with the beam axis at the time of shipment of the in-vehicle radar apparatus. The beam axis is aligned with the reference plane when the radar apparatus is attached to the vehicle.
In practice, the beam axis with respect to the casing deviates from the target value by ±2° to ±3°, while the beam axis with respect to the vehicle is desired to be aligned within ±3°. Thus, the technique disclosed in the above-mentioned publication is used along with various kinds of correction units, and an appropriate one of these correction units is selected to align the beam axis with the reference plane. However, it is troublesome to prepare and manage different kinds of correction units.